Add new type of redirect handlers

lib/inc/drogon/plugins/Redirector.h

@@ -22,11 +22,35 @@ namespace drogon
 {
 namespace plugin
 {
+/**
+ * @brief The RedirectorHandler is a function object that can be registered to
+ * the Redirector plugin. It is used to redirect requests to proper URLs. Users
+ * can modify the protocol, host and path of the request. If a false value is
+ * returned, the request will be considered as invalid and a 404 response will
+ * be sent to the client.
+ */
 using RedirectorHandler =
     std::function<bool(const drogon::HttpRequestPtr &,
                        std::string &,  //"http://" or "https://"
                        std::string &,  // host
                        bool &)>;       // path changed or not
+/**
+ * @brief The PathRewriteHandler is a function object that can be registered to
+ * the Redirector plugin. It is used to rewrite the path of the request. The
+ * Redirector plugin will call all registered PathRewriteHandlers in the order
+ * of registration. If one or more handlers return true, the request will be
+ * redirected to the new path.
+ */
+using PathRewriteHandler = std::function<bool(const drogon::HttpRequestPtr &)>;
+
+/**
+ * @brief The ForwardHandler is a function object that can be registered to the
+ * Redirector plugin. It is used to forward the request to next processing steps
+ * in the framework. The Redirector plugin will call all registered
+ * ForwardHandlers in the order of registration. Users can use this handler to
+ * change the request path or any other part of the request.
+ */
+using ForwardHandler = std::function<void(const drogon::HttpRequestPtr &)>;
 
 /**
  * @brief This plugin is used to redirect requests to proper URLs. It is a
@@ -56,18 +80,40 @@ class DROGON_EXPORT Redirector : public drogon::Plugin<Redirector>,
     void initAndStart(const Json::Value &config) override;
     void shutdown() override;
 
-    void registerHandler(RedirectorHandler &&handler)
+    void registerRedirectHandler(RedirectorHandler &&handler)
     {
         handlers_.emplace_back(std::move(handler));
     }
 
-    void registerHandler(const RedirectorHandler &handler)
+    void registerRedirectHandler(const RedirectorHandler &handler)
     {
         handlers_.emplace_back(handler);
     }
 
+    void registerPathRewriteHandler(PathRewriteHandler &&handler)
+    {
+        pathRewriteHandlers_.emplace_back(std::move(handler));
+    }
+
+    void registerPathRewriteHandler(const PathRewriteHandler &handler)
+    {
+        pathRewriteHandlers_.emplace_back(handler);
+    }
+
+    void registerForwardHandler(ForwardHandler &&handler)
+    {
+        forwardHandlers_.emplace_back(std::move(handler));
+    }
+
+    void registerForwardHandler(const ForwardHandler &handler)
+    {
+        forwardHandlers_.emplace_back(handler);
+    }
+
   private:
     std::vector<RedirectorHandler> handlers_;
+    std::vector<PathRewriteHandler> pathRewriteHandlers_;
+    std::vector<ForwardHandler> forwardHandlers_;
 };
 
 }  // namespace plugin

lib/inc/drogon/plugins/SecureSSLRedirector.h

@@ -66,12 +66,10 @@ class DROGON_EXPORT SecureSSLRedirector
   private:
     bool redirectingAdvice(const HttpRequestPtr &,
                            std::string &,
-                           std::string &,
-                           bool &) const;
+                           std::string &) const;
     bool redirectToSSL(const HttpRequestPtr &,
                        std::string &,
-                       std::string &,
-                       bool &) const;
+                       std::string &) const;
 
     std::regex exemptPegex_;
     bool regexFlag_{false};

lib/src/Redirector.cc

@@ -37,6 +37,10 @@ void Redirector::initAndStart(const Json::Value &config)
                     return HttpResponse::newNotFoundResponse();
                 }
             }
+            for (auto &handler : thisPtr->pathRewriteHandlers_)
+            {
+                pathChanged |= handler(req);
+            }
             if (!protocol.empty() || !host.empty() || pathChanged)
             {
                 std::string url;
@@ -48,10 +52,6 @@ void Redirector::initAndStart(const Json::Value &config)
                                                           : "http://";
                         url.append(host);
                     }
-                    if (pathChanged)
-                    {
-                        url.append(req->path());
-                    }
                 }
                 else
                 {
@@ -64,11 +64,8 @@ void Redirector::initAndStart(const Json::Value &config)
                     {
                         url.append(req->getHeader("host"));
                     }
-                    if (pathChanged)
-                    {
-                        url.append(req->path());
-                    }
                 }
+                url.append(req->path());
                 auto &query = req->query();
                 if (!query.empty())
                 {
@@ -76,6 +73,10 @@ void Redirector::initAndStart(const Json::Value &config)
                 }
                 return HttpResponse::newRedirectionResponse(url);
             }
+            for (auto &handler : thisPtr->forwardHandlers_)
+            {
+                handler(req);
+            }
             return HttpResponsePtr{};
         });
 }

lib/src/SecureSSLRedirector.cc

@@ -49,17 +49,18 @@ void SecureSSLRedirector::initAndStart(const Json::Value &config)
         LOG_ERROR << "Redirector plugin is not found!";
         return;
     }
-    redirector->registerHandler([weakPtr](const drogon::HttpRequestPtr &req,
-                                          std::string &protocol,
-                                          std::string &host,
-                                          bool &pathChanged) -> bool {
-        auto thisPtr = weakPtr.lock();
-        if (!thisPtr)
-        {
-            return false;
-        }
-        return thisPtr->redirectingAdvice(req, protocol, host, pathChanged);
-    });
+    redirector->registerRedirectHandler(
+        [weakPtr](const drogon::HttpRequestPtr &req,
+                  std::string &protocol,
+                  std::string &host,
+                  bool &) -> bool {
+            auto thisPtr = weakPtr.lock();
+            if (!thisPtr)
+            {
+                return false;
+            }
+            return thisPtr->redirectingAdvice(req, protocol, host);
+        });
 }
 
 void SecureSSLRedirector::shutdown()
@@ -69,8 +70,7 @@ void SecureSSLRedirector::shutdown()
 
 bool SecureSSLRedirector::redirectingAdvice(const HttpRequestPtr &req,
                                             std::string &protocol,
-                                            std::string &host,
-                                            bool &pathChanged) const
+                                            std::string &host) const
 {
     if (req->isOnSecureConnection() || protocol == "https://")
     {
@@ -85,21 +85,19 @@ bool SecureSSLRedirector::redirectingAdvice(const HttpRequestPtr &req,
         }
         else
         {
-            return redirectToSSL(req, protocol, host, pathChanged);
+            return redirectToSSL(req, protocol, host);
         }
     }
     else
     {
-        return redirectToSSL(req, protocol, host, pathChanged);
+        return redirectToSSL(req, protocol, host);
     }
 }
 
 bool SecureSSLRedirector::redirectToSSL(const HttpRequestPtr &req,
                                         std::string &protocol,
-                                        std::string &host,
-                                        bool &pathChanged) const
+                                        std::string &host) const
 {
-    (void)pathChanged;
     if (!secureHost_.empty())
     {
         host = secureHost_;

lib/src/SlashRemover.cc

@@ -66,6 +66,31 @@ static inline void removeExcessiveSlashes(string& url)
     removeDuplicateSlashes(url);
 }
 
+static inline bool handleReq(const drogon::HttpRequestPtr& req, int removeMode)
+{
+    static const std::regex regex(regexes[removeMode - 1]);
+    if (std::regex_match(req->path(), regex))
+    {
+        string newPath = req->path();
+        switch (removeMode)
+        {
+            case trailing:
+                removeTrailingSlashes(newPath);
+                break;
+            case duplicate:
+                removeDuplicateSlashes(newPath);
+                break;
+            case both:
+            default:
+                removeExcessiveSlashes(newPath);
+                break;
+        }
+        req->setPath(std::move(newPath));
+        return true;
+    }
+    return false;
+}
+
 void SlashRemover::initAndStart(const Json::Value& config)
 {
     trailingSlashes_ = config.get("remove_trailing_slashes", true).asBool();
@@ -81,36 +106,17 @@ void SlashRemover::initAndStart(const Json::Value& config)
         LOG_ERROR << "Redirector plugin is not found!";
         return;
     }
-    redirector->registerHandler(
-        [removeMode, redirect = redirect_](const HttpRequestPtr& req,
-                                           std::string& protocol,
-                                           std::string& host,
-                                           bool& pathChanged) -> bool {
-            static const std::regex regex(regexes[removeMode - 1]);
-            if (std::regex_match(req->path(), regex))
-            {
-                string newPath = req->path();
-                switch (removeMode)
-                {
-                    case trailing:
-                        removeTrailingSlashes(newPath);
-                        break;
-                    case duplicate:
-                        removeDuplicateSlashes(newPath);
-                        break;
-                    case both:
-                    default:
-                        removeExcessiveSlashes(newPath);
-                        break;
-                }
-                req->setPath(std::move(newPath));
-                if (redirect)
-                {
-                    pathChanged = true;
-                }
-            }
-            return true;
-        });
+    auto func = [removeMode](const HttpRequestPtr& req) -> bool {
+        return handleReq(req, removeMode);
+    };
+    if (redirect_)
+    {
+        redirector->registerPathRewriteHandler(std::move(func));
+    }
+    else
+    {
+        redirector->registerForwardHandler(std::move(func));
+    }
 }
 
 void SlashRemover::shutdown()